Structure for controlling hydraulic pump for driving engine cooling fan of hybrid vehicle

ABSTRACT

A system for controlling a hydraulic pump for operating an engine cooling fan of a hybrid vehicle, which allows a hydraulic pump for driving an engine cooling fan of a hybrid vehicle to be driven by power provided from a transmission PTO of a hybrid vehicle while an engine is idling. Furthermore, the hydraulic pump to be driven may be driven by power supplied from an electric motor when the engine is stopped. As a result, an engine coolant temperature may be properly managed by operating the engine cooling fan of a hybrid vehicle even when the engine is stopped.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119 to Korean Patent Application No. 10-2012-0148346, filed on Dec. 18, 2012, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

1. Field of the Invention

The present invention relates to a structure/system for controlling a hydraulic pump for operating an engine cooling fan of a hybrid vehicle, in particular a bus, and more particularly, to a system for controlling a hydraulic pump for operating an engine cooling fan of a hybrid vehicle, which allows a hydraulic pump to be driven by power provided by a transmission PTO of a hybrid vehicle while idling, and the hydraulic pump to be driven by power supplied from an electric motor when the engine is stopped.

2. Description of the Related Art

In general, a hybrid vehicles typically an engine and a motor as a source of power. Hybrid technology has been able to improve fuel efficiency and emissions and thus has become a very popular vehicle configuration over the last couple of years. In particular, hybrid buses have begun to be developed and used to further improve the effects of large scale transportation on the environment.

In a hybrid bus, a fan driving system for cooling the engine typically uses hydraulic pressure produced by a hydraulic pump to operate the fan. In general, the hydraulic fan driving system is configured to be supplied with power from the engine which is transmitted by a belt which is connected to the engine. Thus, in order for fan to be operated, the engine must be running.

However, when the engine is stopped, for example, when the engine is shut off by an ISG mode (IDLE STOP & GO), because the hydraulic pump, which receives its power from the engine, is also stopped, the coolant temperature is increased by latent heat from the engine because the engine cooling fan not being operated during this time period. The above problem causes an inability to operate the vehicle in an ISG mode for example when the engine coolant temperature is equal to or higher than 98° C., and as a result, the operation rate of the ISG mode deteriorates in summer.

In addition, while performing a regenerative braking (electric retarder) which converts kinetic energy of the electric motor included in the hybrid vehicle into electric energy and performs a brake operation by returning the converted electric energy to an electric power source, when a state of charge (SOC) of a battery is equal to or greater than 80%, the regenerative brake operation is no longer possible. Therefore, as regenerative energy provided by the electric motor may not be utilized, there is a drawback in that auxiliary brake performance deteriorates, thereby increasing consumption of brake pads and discs.

Finally, during operation of the hydraulic pump, because the hydraulic pump is typically limited to a maximum driving torque, marketability may deteriorate due to deterioration in durability of the belt when a size of a fan and the driving torque are increased.

SUMMARY OF THE INVENTION

The present invention has been made in an effort to provide a structure/system for controlling a hydraulic pump for driving an engine cooling fan of a hybrid vehicle, which allows a hydraulic pump for driving an engine cooling fan of a hybrid vehicle to be driven/operated by power provided by a transmission power take off (PTO) of a hybrid vehicle while idling, and the hydraulic pump to be driven by power supplied from an electric motor of a vehicle while the engine is stopped, thereby making it possible to control engine coolant temperatures by operating the engine cooling fan of a hybrid vehicle even when the engine is stopped.

An exemplary embodiment of the present invention provides a system for controlling a hydraulic pump for operating an engine cooling fan of a hybrid vehicle, in which the hydraulic pump is operably connected to a transmission PTO while idling, and operably connected to an electric motor provided in the hybrid vehicle when an engine of the hybrid vehicle is stopped/shut off.

The system may further include an accumulator connected to the hydraulic pump to store hydraulic pressure, in which the hydraulic pressure produced from the hydraulic pump is provided to and preferably stored in the accumulator, and the hydraulic pressure stored in the accumulator is supplied to a fan driving motor for operating the fan. In addition, the hydraulic pump may be driven by brake force generated when a regenerative braking operation is performed, and hydraulic pressure produced by the hydraulic pump may be stored in the accumulator.

Furthermore, when an engine of a vehicle is shut off or stopped, the hydraulic pressure stored in the accumulator may be preferably supplied, and after the hydraulic pressure stored in the accumulator is consumed, the electric motor may be operated to drive a hydraulic motor. In addition, the hydraulic pump may be connected to the transmission PTO and the electric motor via a gear assembly.

The present invention having the aforementioned configurations provides the following advantages.

During regenerative braking, the hydraulic pump may be operated via braking forces generated by the regenerative braking operation, and the hydraulic pump produces hydraulic pressure by being supplied with oil from an oil tank providing the hydraulic pressure, thereby improving auxiliary brake performance.

In addition, because hydraulic energy may be accumulated by the hydraulic pump and the accumulator even when regenerative braking is impossible, for example, even when a state of charge of a battery is equal to or greater than 80%, utilization of regenerative brake force of the hybrid vehicle is increased, and the auxiliary brake performance may be secured even when the state of charge of the battery is equal to or greater than 80%.

Further, because the fan may be operated by the electric motor or the accumulator even in a situation in which an engine coolant temperature is raised as the engine is stopped by the ISG or the like, fuel efficiency is improved due to an increase in operation rate and operation time of the ISG.

Finally, because the hydraulic pump is connected to the transmission PTO and the electric motor by a gear assembly, there is no need for belt and thus the system overall is more durable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a structure for controlling a hydraulic pump for driving an engine cooling fan of a hybrid vehicle according to an exemplary embodiment of the present invention.

FIG. 2 is a view illustrating a path for providing hydraulic pressure for each situation when driving a structure for controlling a hydraulic pump for driving an engine cooling fan of a hybrid vehicle according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

It is understood that the term “vehicle” or “vehicular” or other similar term as used herein is inclusive of motor vehicles in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g. fuels derived from resources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle that has two or more sources of power, for example both gasoline-powered and electric-powered vehicles.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. In a system for controlling a hydraulic pump for operating an engine cooling fan of a hybrid vehicle according to an exemplary embodiment of the present invention. In particular, an electric motor or a transmission PTO 30 is used to power the engine cooling fan in order to prevent the engine cooling fan from being stopped when an engine of a vehicle is stopped by e.g., an ISG mode or the like. Furthermore, in some exemplary embodiments of the present invention the electric motor and the engine cooling fan may be configured to receive driving force by a gear assembly. Therefore, because the hydraulic pump is normally operated even when a regenerative brake operation is performed, auxiliary brake performance is improved and a vehicle maintenance costs are reduced.

The structure/system for controlling a hydraulic pump for driving an engine cooling fan of a hybrid vehicle according to an exemplary embodiment of the present invention, which is configured as described above, is illustrated as a block diagram of FIG. 1.

As illustrated in FIG. 1, a hydraulic pump 10 of an exemplary embodiment of the present invention is connected to an electric motor 20 or a transmission PTO 30, instead of an engine to which a hydraulic pump 10 of the related art was connected, in order to be supplied with power from the electric motor 20 or the transmission, and configured to be supplied with power using the gear assembly as a connection source without using a belt of the related art.

Therefore, in the system for controlling the hydraulic pump 10 for driving an engine cooling fan of a hybrid vehicle according to the present invention, which is configured as described above, even though the engine is stopped by e.g., an ISG mode or the like, the engine cooling fan may be normally operated by operation of the electric motor 20 which is operated by receiving electric power from a battery of the vehicle, and therefore there is an advantage in that an engine coolant temperature may be maintained even when an ISG mode is initiated.

Meanwhile, the present invention further may include an accumulator 40 for storing the hydraulic pressure produced from the hydraulic pump 10. The accumulator temporarily stores the hydraulic pressure provided from the hydraulic pump 10, and is configured to store hydraulic energy produced by the hydraulic pump 10 which is driven by the electric motor when a state of charge of the battery is equal to or greater than 80%.

FIG. 2 is a view illustrating a path for providing hydraulic pressure for each situation when driving a structure for controlling a hydraulic pump 10 for operating an engine cooling fan of a hybrid vehicle according to an exemplary embodiment of the present invention.

As illustrated in FIG. 2, when the regenerative brake operation of the vehicle is performed, the hydraulic pump 10 is operated by brake force generated by the regenerative brake operation, and as a result, the hydraulic pump 10 produces hydraulic pressure by being supplied with oil from an oil tank providing the hydraulic pressure. The hydraulic pressure produced by the hydraulic pump 10 is provided to an accumulator 40 to be stored in the accumulator 40. Therefore, utilization of regenerative brake force of a hybrid vehicle is increased, and the auxiliary brake performance may be secured even when the state of charge of the battery is equal to or greater than 80%.

Meanwhile, when the engine is stopped by the ISG mode or the like, that is when the coolant temperature is increased to be equal to or higher than 98° C. while the ISG mode is active, the hydraulic pressure may be produced by using the hydraulic pressure stored in the accumulator 40 or power which is produced by driving the electric motor of the vehicle. In this case, the hydraulic pressure stored in the accumulator 40 may be preferably provided to a hydraulic motor via a pressure control apparatus, and thereafter the electric motor may be driven to produce the hydraulic pressure. Therefore, even in the ISG mode, the coolant temperature of the engine may be managed, and an effect of increasing an operation rate of the ISG may be obtained.

While the exemplary embodiment of the present invention with respect to the system for controlling the hydraulic pump 10 for driving an engine cooling fan of a hybrid vehicle has been described in detail above, the exemplary embodiment is only a specific example for easy understanding of the present invention, and the present invention is not limited thereto. Here, it is obvious to a person skilled in the art that besides the exemplary embodiments disclosed herein, various modifications can be made based on the technical spirit of the present invention. 

What is claimed is:
 1. A system for controlling a hydraulic pump for operating an engine cooling fan of a hybrid vehicle, wherein the hydraulic pump is configured to be operated via power from a transmission PTO while an engine is idling, and configured to be operated via power from an electric motor when the engine is stopped.
 2. The system of claim 1, further comprising: an accumulator connected to the hydraulic pump to store hydraulic pressure generated by the hydraulic pump, wherein the hydraulic pressure produced from the hydraulic pump is provided to and stored in the accumulator, and the hydraulic pressure stored in the accumulator is utilized to operate a fan driving motor for operating the cooling fan.
 3. The system of claim 2, wherein the hydraulic pump is driven by brake force generated when a regenerative brake operation is performed, and hydraulic pressure produced by the hydraulic pump is stored in the accumulator.
 4. The system of claim 2, wherein when an engine of a vehicle is stopped, the hydraulic pressure stored in the accumulator is supplied, and after the hydraulic pressure stored in the accumulator is consumed, the electric motor is operated to drive a hydraulic motor within the hydraulic pump.
 5. The system of claim 1, wherein the hydraulic pump is connected to the transmission PTO and the electric motor by a gear assembly.
 6. A system comprising: a pump configured to operate an engine cooling fan of a hybrid vehicle, a transmission power take off (PTO) operably connected to the pump; and an electric motor operably connected to the pump, wherein the pump is operated by the transmission PTO while an engine is idling, and the electric motor when the engine is stopped.
 7. The system of claim 6, wherein the pump is a hydraulic pump.
 8. The system of claim 7, further comprising: an accumulator connected to the hydraulic pump to store hydraulic pressure generated by the hydraulic pump, wherein the hydraulic pressure produced from the hydraulic pump is provided to and stored in the accumulator, and the hydraulic pressure stored in the accumulator is utilized to operate a fan driving motor for operating the cooling fan.
 9. The system of claim 8, wherein the hydraulic pump is driven by a brake force generated when a regenerative brake operation is performed, and hydraulic pressure produced by the hydraulic pump is stored in the accumulator.
 10. The system of claim 8, wherein when an engine of a vehicle is stopped, the hydraulic pressure stored in the accumulator is supplied, and after the hydraulic pressure stored in the accumulator is consumed, the electric motor is operated to drive a hydraulic motor within the hydraulic pump.
 11. The structure of claim 7, wherein the hydraulic pump is connected to the transmission PTO and the electric motor by a gear assembly. 